Liquid-fuel injection means for prime movers



LIQUID-FUEL INJECTION MEANS FOR PRIME MOVERS Filed Dec. 27, 1948 2 SheetsSheet l Oct. 20, 1953 T. A. HARRIS 2,655,937 LIQUID-FUEL INJECTION MEANS FOR PRIME MOVERS Filed Dec. 27, 1948 2 Sheets-Sheet 2 Patented Oct. 20, 1953 LIQUID-FUEL INJECTION MEANS FOR PRIME MOVERS Thomas Alfred Harris, Birmingham, England, as-

slgnor to Joseph Lucas Limited, Birmingham,

England Application December 27, 1948, Serial No. 67,464 In Great Britain January I, 1948 3 Claims.

The invention relates to liquid-fuel injection systems for prime movers, and of the kind comprising a pump driven by the prime mover, and a delivery nozzle or nozzles through which the fuel is supplied to a combustion chamber from the pump. When the prime mover is initially set in motion by an electric motor or other external source of power, the speed of rotation may be insufiicient to enable an adequate delivery to be obtained from the pump to ensure prompt and effective starting of the prime mover under its own power. To meet this condition I have employed an accumulator (as described in the specification or" British Letters Patent No. 552,725) which is charged by the pump during the starting operation, and a release valve adapted to control the supply of liquid fuel from the pump and accumulator to the nozzle or nozzles, the valve being adapted to be opened automatically when a predetermined quantity of fuel has been stored, or when a predetermined fuel pressure is reached, in the accumulator.

For some purposes it has been found desirable to obviate or minimise the possibility of recharging of the accumulator during normal working of 7 the prime mover, as, for example, when the speed of the latter is being accelerated, and the object of the present invention is to enable this requirement to be met in a simple and satisfactory manner.

The invention comprises the combination of a cylindrical accumulator chamber, a spring loaded piston slidable in'the chamber, a spring loaded release valve between one end of the chamber and a delivery outlet, and a restricted branch passage connecting the end of the chamber remote from the inlet to the delivery side of the valve.

In the accompanying drawings:

Figures 1, 2 and 3 are sectional views illustrating diagrammatically three different embodiments of the invention.

Referring to Figure 1, I employ a body part it having therein a cylindrical accumulator chamber one end of which is in communication with an inlet b. Within the chamber is arranged a piston c loaded by a spring at, and in the end of the chamber remote from the inlet is provided a non-return valve e which (when open) communicates with the outer atmosphere. Alternatively it may communicate with a tank or other suitable part of the system associated with the accumulator, for the free admission of fuel to the accumulator.

Between the outlet f and the end of the chamher which receives fuel from the inlet 1) is arranged a release valve. This may consist of a closure member g co-operating with a seating '71. and carried by a diaphragm i or piston loaded by a spring 9'. The region at the discharge side of the seating is also in communication with the remote end of the chamber by way of a branch passage k which includes a restricted orifice m which may be provided in any convenient manner.

The arrangement is such that when the prime mover is set in motion by an external power source, the fuel pump first charges the accumulator. When a predetermined pressure is attained in the accumulator, the discharge valve g opens and liquid fuel then passes to the nozzle or nozzles jointly from the pump and the accumulator, the latter providing a sufficient quantity of fuel to ensure prompt starting of the prime mover under its own power. During the discharge of the accumulator by the movement of the piston under the action of its spring, air or other fluid flows freely into the remote end of the chamber from the atmosphere through c, enabling the piston tomove quickly. Also liquid fuel can enter the remote end of the chamber at a relatively slow rate from the discharge side of the release valve along 70. Consequently while the prime mover is operating normally, the remote end of the chamber contains both air and liquid fuel under pressure which balances the pressure exerted on the piston by the fluid entering at b. When at any time thereafter the prime mover is accelerated with accompanying temporary increase of pressure in the end of the accumulator through which the liquid fuel flows from the pump to the nozzle or nozzles, a displacement of the piston may occur, but this is relatively small and not suificient to allow such an accumulation of fuel to occur in the accumulater as might have a temporary undesired effect on the normal rate of supply of fuel to the prime mover. During displacement of the piston by the entering fuel, the contents of the chamber beneath the piston are discharged to the outlet 1 along the passage is.

The example shown in Figure 2, is essentially similar to that shown in Figure 1, and differs in that a by-pass passage n containing a non-return valve 0 loaded by a spring p is provided in association with the passage k. During the charging of the accumulator, fluid from the lower part of the chamber can be displaced rapidly to the outlet I through the by-pass passage n. The admission of fluid to the lower part of the chamber 3 when the valve 9 is opened occurs at a restricted rate along the passage is.

In the example shown in Figure 3, the lower part of the chamber is provided with a discharge passage q leading to an outlet 1' which is open to atmosphere or a sump. The outlet r is controlled by a closure member s loaded by a spring t, the said closure member being operable against the action of its spring by the pressure of fluid in the passage k. Between the passages k, q is arranged a by-pass passage u containing a nonreturn valve 12 loaded by a spring w.

During the filling of the accumulator, the contents of the chamber beneath the piston are discharged freely through a. When the valve 9 is opened the pressure of the fluid in 7a causes the member s to close the outlet 1", and fluid can then flow from k: to the chamber past the valve 2;. Otherwise the action of the apparatus is the same as that of the examples shown in Figures 1 and 2.

The invention is not, however, restricted to the said examples, as subordinate details may be varied to meet different requirements. Thus, the valve e is not always essential and may be omitted. When this valve is not used the action is as follows:

Looking at Figure 1, and starting with the piston in its upper position, the lower part of the chamber a is then occupied by air and some liquid. On charging the chamber by liquid admitted at b the piston descends and the liquid in the lower part of the chamber together with (possibly) some air is displaced along the passage 7c. When the valve closure member g opens the piston is returned by the action of the spring d at a rate which is greater than that at which fluid can flow to the lower part of the chamber a through the restricted orifice Consequently the greater part of the liquid displaced by the piston from the upper part of the chamber past the closure member 9 will be discharged through the outlet f. Subsequently while liquid is flowing from the inlet b to the outlet 1, some liquid will flow past the restriction m and along the passage lc to the lower part of the chamber a, and compress the air entrained therein. By suitably proportioning either the volume of the chamber a below the piston c, or by making the spring d of appropriate strength, or by both of these devices, the valve e may be dispensed with, but for most purposes it is usually desirable to employ this valve.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. For use in liquid fuel injection systems of the kind specified, an accumulator comprising the combination of a cylindrical accumulator chamber having an inlet and a delivery outlet, a spring loaded piston slidable in the chamber, a

4 spring loaded release valve between one end of the chamber and the delivery outlet, and a restricted branch passage affording a connection between the other end of the chamber and the delivery side of the said release valve when the latter is open and being controlled by said valve, whereby when fuel is being discharged through the open release valve, some fuel can flow to the said other end of the chamber through the restricted branch passage.

2. For use in liquid fuel injection systems of the kind specified, an accumulator comprising the combination of a cylindrical accumulator chamber having an inlet and a delivery outlet, 2.

spring loaded piston slidable in the chamber, a

, spring loaded release valve between one end of the chamberand the delivery outlet, a restricted branch passage affording a connection between the other end of the chamber and the delivery side of the said release valve when the latter is open and being controlled by said valve, a bypass passage associated with said restricted branch passage, and a non-return valve in said by-pass passage preventing flow therein towards the said other end of the accumulator chamber, whereby when fuel is being discharged through the open release valve some fuel can flow to the said other end of the chamber through the restricted branch passage, and fuel can be displaced rapidly from the said other end of the chamber to the outlet when the accumulator is being charged.

3. For use in liquid fuelinjection systems of the kind specified, an accumulator comprising the combination of a cylindrical accumulator chamber having an inlet and a delivery outlet, a spring loaded release valve between one end of the chamber and the delivery outlet, a restricted branch passage affording a connection between the other end of the chamber and the delivery side of the said release valve when the latter is open and being controlled by said valve, a discharge passage in communication with the said other end of the chamber, a spring loaded valve controlling the said passage and operable by fluid pressure in the branch passage, a by-pass passage between the said branch and discharge passages, and a non-return valve in the by-pass passage.

THOMAS ALFRED HARRIS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,959,640 Peters May 22, 1934 2,005,832 Vidalie June 25, 1935 FOREIGN PATENTS Number Country Date 552,725 Great Britain Apr. 21, 1943 

